With means presently available, mainly surgery and radiation, most cancers can be cured if the diagnosis is made before the cancer has spread too far to permit removal by the surgeon or destruction by radiation. They require a biopsy for a diagnosis. The pathologist can find one of the following: (1) he can exclude cancer; (2) he finds changes leaving no doubt as to the malignant nature--the cancer may at that time be already invasive; (3) ana ;asia may be of moderate degree or (4) cells with morphologic criteria of cancer may be seen side by side with normal cells (carcinoma0in-situ). It has been established by follow-up of patients with carcinoma-in-situ of the cervix that some such lesions are reversible. The highly sensitive Red Cell Adherence Test, based on the detection of antigen A, B and H in tissues permits (1) to diagnose some carcinomas earlier than is possible with any other method available at the present time and (2) to demonstrate the possibility or even probability of metastases, or to exclude their presence. We will continue to test the validity of our results by studying early and advanced cancers of different organs, prospectively and retrospectively.